This invention relates generally to the containment of hazardous material in an enclosure, and, more particularly to the containment within a mail tub of a biological agent or the like disposed on or in a mail piece.
The recent incidents of anthrax laced letters being transported through the United States Postal Service (USPS) facilities to unsuspecting recipients has alarmed the nation and the world. Currently, the tainted letters are discovered after the recipient accepts delivery or by alert postal employees noticing white powder that could be anthrax on mail parcels, sorting and distribution equipment, or themselves. There appears to be few current security devices or procedures that are available to intercept such letters at the earliest source of introduction into the USPS system, for example at the mailbox or post office drop box. Also, there appears to be no known devices or procedures that safe guard against biological agents in forms other than a white powdery substance, such as anthrax.
Currently when there is suspicious mail, it is all bulk irradiated as was done during the recent anthrax problem thereby delaying some mail for months and damaging or destroying some of the mail due to problems caused by the irradiation. For example some of this irradiated mail became brittle and pieces broke off.
Almost all mail articles at one time or another are collected and transported to postal facilities by way of mail tubs. Therefore, mail tubs can be the first point of containment if a hazardous material is detected prior to the exposure of its air and contents at a postal facility.
Some mail tubs have lids or covers, but they are not airtight vessels. Mail articles that contain hazardous material within or on the outer surface contaminated not only the other mail articles within the mail collection tub, but also the mail collection tub air. The agitation of the mail collection tub in transport or by routine handling by the postal employees can cause the hazardous material to form a plume or aerosol. There is also a threat of contaminating postal employees by inhaling the contaminated air as well as by direct contact to skin tissue.
U.S. Pat. No. 3,915,339 discloses use of pressurized air into a container to loosen and cause free flow of material therein move.
U.S. Pat. No. 4,580,440 discloses a method of detecting a contraband substance in freight cargo in which the container is agitated to disturb particulates therein and samples are taken of the air containing such particulates. The collected particulates are heated to drive off vapors indicative of the contraband substance and the vapors are analyzed in a mass analyzer.
U.S. Pat. No. 4,593,816 discloses a container for storing and transporting letter mail and other flat articles having walls with rib members including on the bottom and the cover to provide structural integrity for the container. The ribs are vertically positioned along the height of the walls and continue across the bottom to form similar verticals ribs on the opposite wall. Adjacent ribs can be made so that dividers can be supported between them. The containers are arranged to be nested when the covers are off and stacked when the covers are on.
U.S. Pat. No. 5,700,426 discloses a method for decontaminating or sterilizing “in situ” a vacuum sealed container and device for implementing such method for sterilizing or decontaminating microorganisms or dangerous products.